1. Field of the Invention
The present invention relates to a method for recording a plurality of kinds of data on an information recording median and for reproducing the recorded data.
2. Related Background Art
Hitherto, as information recording media, a floppy disk for recording and reproducing information by using magnetism, a card-shaped optical information recording median (hereinafter, referred to as an optical card) for recording and reproducing information by using light, and the like are known. To manage the information of those information recording media, auxiliary data comprising a directory is used to manage the data for every file, in order to store a large capacity of data. As shown in FIG. 1, generally, file information such as a file name, file length, leading data track number, and the like are written into the directory and a file management of a data track portion is executed.
In general, the foregoing optical card, particularly, an unerasable write once type optical card has a size near a credit card. In spite of such a small size, the optical card has a large recording capacity. The dimensions of a credit card are set to about 85 mm.times.55 mm. Now, assuming that an information track pitch is set to 20 .mu.m and a recording length of one bit is set to 5 .mu.m,
The number of tracks: 55/(20.times.10.sup.-3)=2750 PA1 Bit capacity/track: 85/(5.times.10.sup.-3)=17000 (bits) PA1 Byte capacity/track: 17000/8=2000 (bytes) PA1 preparing a single directory block including a plurality of sectors for an area different from the data blocks on the recording surface; accessing one of the plurality of blocks on the basis of the kind of data; recording data on at least one sector in the accessed block; and recording a directory to manage the data on at least one sector in the directory block, wherein the directory corresponding to the data recorded in any one of the data blocks is also recorded on the single directory block.
To manage such a large capacity of information, a managing method of information by the directory is needed.
FIG. 2 is a schematic plan view showing an example of an optical card. In FIG. 2, an optical card 1 has a data portion 10 (10.sub.1, 10.sub.2, . . . , 10.sub.n) comprising data tracks and a directory portion 20 (20.sub.1, 20.sub.2, . . . , 20.sub.n ) . In a case of recording information on the optical card 1, data is written into the data portion 10 from the upper portion in the direction indicated by an arrow E. Directory information as data management information is written into the directory portion 20 from the lower portion of the optical card 1 in the direction indicated by an arrow D in a write-once manner.
The data recording method as shown in FIG. 2, is a relatively suitable method because the number of directories is small when handling a file of a relatively large file size. In a case of recording a number of files each having a very small size, however, the number of directories increases in accordance with such a large number of files, so that there is a problem such that when data is reproduced, a reading time of the directory becomes long, so that an accessing time increases. On the other hand, even when data is recorded or is logically rewritten, the corresponding directory must be recorded into the directory portion, so that there is a problem such that the seeking operation of the recording and reproducing head of the recording and reproducing apparatus is complicated.
Further, according to the data recording method shown in FIG. 2, since the data files are written in the E direction shown in FIG. 2, the necessary files are not always arranged in accordance with the correct order upon reproduction. For example, when it is now assumed that there is an information recording medium on which a certain doctor has recorded data such as electrocardiogram information and electroencephalogram information of a patient for a period of ages from 1 to 15, the electrocardiogram information and electroencephalogram information at the age of one year of the patient, the electrocardiogram information and electroencephalogram information at the age of two years, and the like have once been written on the information recording medium. When the user tries to reproduce only the electrocardiogram information from the information recording medium, the data files are accessed in a skipping manner. Therefore, there is a problem such that the accessing time is longer than that in the case where only the electrocardiogram information has sequentially been once written. On the other hand, in the case where a region in/from which no information can be recorded or reproduced exists in the information recording medium because there is a large defect in the medium, it is difficult to use the medium while avoiding such a region by the conventional method in spite of the fact that such a using method is desirable to improve a recording or reproducing speed.
To solve such a problem, there has been proposed an example in which a plurality of blocks are provided, in which each block has a data portion to record a data file and a directory portion to record directory information in order to manage the data files as shown in U.S. Pat. No. 4,998,009 (corresponding to European Patent No. 286308) . The above method will now be described with reference to FIG. 3. In FIG. 3, reference numerals 50.sub.n, 50.sub.n+1, . . . , 50.sub.n+n denote blocks which are arranged on the optical card 1; 60.sub.n1, 60.sub.n2, . . . , 60.sub.nn indicate information recording areas (data portions to record data files) of the block 50.sub.n ; and 70.sub.n1, 70.sub.n2, . . . , 70.sub.nn show directory areas of the same block 50.sub.n, respectively. A plurality of blocks 50.sub.n+1, . . . , 50.sub.n+n each having a construction similar to the block 50.sub.n are arranged on the optical card 1. The directories to manage the data files are also recorded in the same block. The user who uses the information recording medium can select a desired block. An information retrieving speed can be increased by such a selection.
According to the above method, when it is now assumed that there is an information recording medium such that a doctor tries to record electrocardiogram information into the block 50.sub.n and electroencephalogram information into the block 50.sub.n+1 and that the doctor wants to reproduce only the electrocardiogram information from the information recording medium, the data can be continuously reproduced in the block 50.sub.n. Therefore, an accessing time can be reduced On the other hand, as shown in FIG. 3, when the presence of a defect 80 is detected, the blocks can be arranged so as to avoid such a defect 80.
According to the data recording method shown in FIG. 3, however, by dividing the data portion into a plurality of blocks, the data to be recorded can be recorded in a state in which the data can be easily read out by the will of the user in accordance with a situation of using the information. However, since information such as leading data track number and the like of the data file has been recorded in the directory information, the directory must be read before the data file is reproduced. Moreover, since the directories have been distributed and recorded into the blocks in the optical card, there is a problem such that a reading time of the directories is long and a data reproducing time is also long.